Method for measuring distance.



R. A. FESSENDEN.

METHOD FOR MEASURING DISTANCE.

APPLICATION FILED APR. 2. 1914.

4 Patented b; 27,1917;- 17.

WITNESSES:

v f I lNl/EIVgQR M I Mo. 6. v 7M1! d w .54%? v y I I 02/4/4 A TTORNEY6 UNITED STATES PATENT OFFICE.

REGINALD A. FESSENDEN. OF BROOKLIN E, MASSACHUSETTS, ASSIGNOR TO SUBMARIN'E SIGNAL COMPANY, OF WATERVILLE. MAINE, A CORPORATION OF MAINE.

METHOD FOR MEASURING DISTANCE.

Specification of Letters Patent. Patented F b. 27 1917 7 Application filed Apri12, 1914. Serial No. 828,972.

To all whom it may concern:

Be it known that I, REGINALD A. FEssnN- "man. of Brookline, in the county of Nor-,

folk and Stateof Massachusetts, a citizen of the United States, have invented a new and useful Improvement m Methods for Measuring Distance, of which the following is a specificationl The invention described herein relates to methods and apparatus whereby having given, or having ascertained two or more of the following quantities, i. 6. time, distance, intensity and medium, one ormore of the remaining quantities may be determined.

For example, being given the distance be tween two points in a mine and having detcrmined the time taken by a sound wave to travel between the two points, it is possible to draw conclusions with regard to the probable nature of the rock between the two points; or if an echo beobserved or a re-' fraction of the sound, it is possible to es timate the distance of the reflecting or refracting vein.- v I Again, if a sound be produced on-a'. ship and the time elapsin'gbetween-the productio n of the sound and its echo from the bottom be determined, it is possible to deter from another ship, it is possible to determine how far the iceberg is from the ship.

The invention relates especially to sounding, but is not limited to measuring distance in a vertical direction, or in a single medium, being applicable to all directions and mediums, and to determine other quantities besides distance as stated above, for example the nature of the med1ux n.-

he accompanying drawing forming a .part of this specification shows diagram-- matically' apparatus suitable for use in connection with my invention.

lack of any method'f' lwhich was, practical and of the lackof any practical appara- If the layer f era-bly the oscillator described tus. For example, if a ship drawing twenty-I five feet. was running up a channel having a depth of fifty feet, the time taken by the sound of a. bell in traveling from the 'bottom of the ship to-the bottom of the channel and back to the ship would be only about one one-hundredth of a second, and to determine the depth to within one foot would necessitate knowing the time elapsing between the time at'which the bell clapper struck the bell and the time at which the echo returned to the nearest four ten-thousandths of a second which is impossible by any method heretofore suggested or in use.

In addition, since the sound of the blow of the bell would be heard in the receiving apparatus,- the car would be rendered insensitive and the echo would'not be heard,-.being much fainter and being drowned out by the vibration of the bell persisting after the clapper had struck. a

My method comprises a. number of new features, and while all of them are not necessarily used in combination in all cases, they are peculiarly adapted to cooperate to give goold results in the cases most commonly met wit w One of these features is that the production and echo reception are electrically interlocked, so that the time elapsing between them is determined by the time elapsing between two electrical phenomena,

and can be determined with great accuracy. A second is that the receiver is. cutout while the sound is being produced and the sound producer; is cut out while the sound 4 is being received.

A third is that the sound impulseis produced over a definite time and at adefinite intensity and then ceases abruptly, instead of dying away gradually.

A fourth'feature is that the depth may. be recorded graphically on a moving tape.

A fifth feature is thatthe same apparatus (a magnetophone, for example,)' maybe. used to produce the sound and to receive A sixth feature is that the electric im-E' pulse' used for producing the sound by the motion of the current carrying conductor That distance could theoretically be'"determined by sound echoes has long 'bBGIlLf' known, but this knowledge'z -hasnever been put ,into commercial on acconntzof the maybe derived from a direct'current source, There-are other features which will be apparent from the description, and, are {novel in'method'and apparatus.-

States Patent No. 1,167,366, dated January 4, 1916. Here 12 is the diaphragm which being immersed in water in the fore peak of a vessel, or inserted in the skin of the ship, by its motion produces the sound. 13 and 14 are the terminals of a fixed winding 37 on the core 36, and 15 is a movable co per tube attached to the rod 18 by the dis is 38, 39, which rod is fastened to the diaphragm 12. 16is an electromagnet excited by the coil 17. When an alternating or fluctuating current passes through the core winding 37 currents are induced 1n the copper tube 15 by transformer action, and the tube being in the strong magnetic field generated by a direct current in the coil 17, oscillates with great force, and actuates the diaphragm 12, producing a sound which ceases immediately the electric current ceases to pass through the winding 37.

A wheel or commutator 28 of insulating material and having a metallic segment 30,

is rotated at a definite speed by the motor 29. The battery or other source of voltage indicated at 20 and the ammeter 19 are connected to the brush 21 and one terminal 13 of the winding 37, and the brush 22 is connected to the other terminal 14.

When the brushes, 21, 22 both rest on the conducting segment 30, the battery 20 sends an electric impulse through the-winding 37 and the diaphragm 12 is pushed out or in producing a sound in the water, and this occurs at each revolution of the. commutator 28.

In this way a musical note is produced whose pitch will depend upon the number of revolutions per second of the commutator 28.

The oscillator above described also acts as a sound receiving transmitter for on a sound wave striking the diaphragm 12, it is moved in and moves the tube 15 whiclubeing a conductor moving in a magnetic field, has a current generated in it by the movement, and this current in turn generates a current in the fixed winding 37 by transformer action, which flows out by the terminals 13, 14 to the brushes 41, 42 on the hard rubber wheel 51, thence, when the conducting segments 50 pass beneath them, to the brushes 43, 44, and thence through the telephone receiver 23 and recording apparatus 35, either or both of which may be termed an indicating mechanism, to the two-way switch 49, and thence to the brushes 25, 26, whenever the two-Way switch is closed to the right and the segment 30 of the wheel 28 passes beneath the brushes, thus completing the circuit.

It will be seen that the telephone receiver circuit is only completed when the segments 30 and 50 pass beneath the brushes in the receiver circuit, and that this will occur at some time later than the segment 30 has passed beneath the brushes 21, 22 generating the sound. Consequently no sound will be heard in the telephone receiver 23 until the brushes 41, 42, 43, 44, 25, 26 are shifted by the movable arm 27, to which they are attached, to such a position that the segments 50, 30 pass under them at exactly the instant'that the echo from the sound has come back from the bottom andstruck the diaphragm 12.

And it will be apparent, since the wheels 28 and 51 revolve at a fixedspeed, that the angle through which the brush arm 27 is moved will be a function of'the distance of the. reflecting bottom, and that the apparatus may be so constructed and graduated that this distance can be read off directly on the scale 33 in feet.

To ascertain in the first place whether there is any iceberg, for example near enough to produce an echo receivable on board a shipvcarrying the sounder, I prefer to cut out the brushes 41, 42, 43, 44 by the switch 52 and to throw in the double pole switch 49 so as to connect the receiver circuit to the metal wheel 47 which carries the insulating segment 48. This segment 48 is so located on the periphery of the wheel 47 that as the wheel 47 rotates the segment. 48 passes under the brushes 45, 46 and breaks the circuit through them at exactly the instant the battery circuit is closed and its current generates a sound, that is, at exactly the instant the brushes 21, 22 rest on the conducting segment 30 so that the re ceiver circuit is always closed through the oscillator except at the instant the sound is being generated. During this period the receiver is always receptive except at the moment sound is being sent out and as soon as the receipt of echoes begins they will be received at the indicating mechanism. When so received the switches 49 and 52 are thrown back so that the brushes 45, 46 are cut out and the brushes 41, 42, 43, 44 are cut in and the process of determining the distanceof the reflecting surface (iceberg) is carried on as before described. r

The metal wheel with its connecting mechanism serves therefore for a preliminary observation only as it will give exactly the moment when the first echo is received (fm a vessel approaching a reflecting surace;

Instead of this the brush arm may be shifted until the musical note or echo is picked up, but by this course it is, not so certain that the first indication of echo will be received because it may. come while the circuit through the brush arm connection is'open.

It will of course be understood that as shown in the drawing the segments 48 and 30 are not in proper relation to secure the above result. A proper adjustmentof the wheel 47 on its axis yvould remedy this 130 opened at. the ends ofboth leads to the re-' ceiver. The wheel 51 accomplishes'this by having two conducting segments 50 side by side on its periphery, one of which engages the brushes 41, 44 and the other 42, 43. When these brushes do; not rest on the segments 50 the circuit is broken on both sides of the receiver. At 34 is shown means for measurin the intensity of the sound which may be u ed if desired. This device is a-variable resistance aid is operated by throwing in resistance until the sound is modified so as to be just audible and taking account of the amount of resistance thrown in, then by performing the same operation whenanother sound is received. By comparing the amount of resistance thrown into circuit in each case the intensity of the sounds are measured com paratively.

The apparatus may be used to locate icebergs or geological strata or other reflecting bodies. For measurement of long distances the speed of rotation of 28 may be slow, or an'ordinary, stop watch used to measure the time intea'dof shifting. the arm 27. For

icebergs along wave length ispreferably.

used to insure reflection or diffraction fringes. The wave length may be as long as 100 feet or more. I In place of connecting the source of sound '11 to the echo indicating mechanism 23, 23 maybe connected, by throwing the-switch 53 to the position shown by dotted lines so as to connect a second receiving transmitter '54, 11 being used for producing the sound and 54 being used for receiving the echo.

' This method is especially valuable when the depthof sounding is small and when r the diaphragm 12 does not come to rest with suflicient abruptness.

Another. method of accomplishing this,

i bringing the diaphragm to rest substantially,instantaneously is by placin a resistance 55, preferably non-inductive, across the terminals of the oscillator as shown.

The method is also distinguished from previous methods in that the electric forces act directly upon the diaphragm to set it in' motion to produce sound instead of first acting upon an intermediate mechanism such as a hammer and then causing the hammer to impact uponthe diaphragm and thereby produce the sound. The omission of the intermediate mechanism greatly increases the efliciency of the apparatus.

What I claim as my invention-is:

1. The method of measuring distance by sound inflection, which consists in varying the currentin an electric circuit at the sending end, setting up at the sending end sound vibrations identical in time with the current variations in said electric circuit, directing said sound vibrations against an objective, transforming the sound vibrations inflected by said objective when received into electric impulses identical in time with said received sound vibrations and measuring the time elapsing between -the beginning of each set of electric impulses.

2. The method of measuring distance by sound inflection which consists in varying the current in an electric circuit at the sending end, setting up at the sending end sound vibrations identical in character with the current variations in said electric circuit, directing said sound vibrations against an objective, transforming the sound vibrations inflected by said objective when received into electricimpulses identical in character with said received sound vibrations and v measuring the time elapsing between the beginning of each set of electric impulses.

T e method of measuring distance by measuring the time lelapsing between the beginning of each setof electric impulses.

sound inflection which consists in-varying 4. The method of measuring distance by sound inflection which consists in varying the purrent in an electric'cir'ouit at the sending end, setting up at the sending end sound vibrations identical in time, character. and

frequency with the current variations in said electric circuit, directing said sound vi-' brat-ions against an objective,transforming the sound vibrations inflected by said objective when received into .electric impulses identical in time, .character and frequency with said received sound vibrations and measuring the time elapsing between the be- I ginning of each set of, electric impulses.

5. That method of measuring distance by sound inflection which consists in transforming electrical impulses into sound vibrations for a predetermined period, which ,sound vi-' brations are directed against the objective, transforming the sound vibrations which are inflected by said objective into electrical impulses and measuring the time between the commencement of said predetermined period and the first receipt of said inflected im pulses.

6. lilechanisru for measuring distance comprising av sounder, a receiving mechanism comprising a receiving transmitter and an indicating mechanism, means for operating the sounder and means adapted to operate autonmtieally when the sounder is silent to connect the receiving transmitter and the indicating mechanism.

7. Mechanism for measuring distance comprising a sounder. a receiving transmitter, an indicating meelmnism, means for operating the sounder intermittently, time measuring means operable when the sounder is silent for connecting the receiving transmitter with the indicating mechanism, and sound picking up means operable at all times when the sounder is silent for connecting the receiving transmitter with the indicating mechanism.

8. Mechanism for measuring distance comprising a, sounder, a receiving transmitter, an indicating mechanism, means' for operating the scan er intermittently, time measuring means 0 erable momentarlly when the sounder is si ent for connecting the receiving transmitter with the indicating mechanism, and sound p1ck1ng up means 0p erable at all times when the sounder is silent for connecting the receiving transmitter with the indicating mechanism, sald two con heating means being inoperable simultaneously.

9. Mechanism for measuring distance comprising a sounder, means for operating it, a receiving mechanlsm compris ng a receiving transmitter and an indicat ng mechanism, a broken circuit connecting said receiving transmitter and sa d indicating mechanism, a serieskofbrushes and meansv for adjusting their posltlon to close said broken .cireuit, whereby said broken circuit may be closed when sald sounder is silent and said receiving transmltter 1s energized.

10. Mechanism for measuring dlstance comprising a sounder, means for operating it, a receiving transmittenand an indicating mechanism, a broken circuit conne'ctmg sa1d receiving transmitter and sald indicating mechanism, a series of brushes, and means for adjusting their position to close said broken circuit, whereby said circuit may be closed when said sounder is silent and said receiving transmitter is energized, and means whereby the adjusted position of said brushes ma. 'be measured.

11. In a device o the kind described, an electromagnetic mechanism operable both to produce and receive impulses, means for energizing said mechanism to produce 1mpulses, and meansoperable when said impulse-producing mechanism 1s 1noperat1ve to enable said mechanism to receive impulses.

12.'In a device of the kind described, a sounder and a receiving transmitter, means for energizing said sounder comprising a source. of electricity, a rotary wheel of insulating material having a contact thereon, brushes engaging said wheel and periodically engaging said contact, connectlons between said brushes, said source of electricity and said sounder, an indicator, and connections between said receiving 'transmitter and said indicator operable only when said sounder is silent.

13. In a device of the kind described, a sounde' and a receiving transmitter, means for energizing said sounder comprising a source of electricity, a rotary wheel of insulatingmaterial having a contact thereon, brushes adapted to engage said contact, connections between said brushes, said source of electricity and said sounder, an indicator, a second set of brushesalso adapted to engage said contact, and connections between said second set of bruslies and said telephone receiver comprising an automatic circuit breaker adapted to break said. circuit when said sounder is ener ized.

14. In a device bf'the ind described, a sounder and a receiving transmitter, means for energizing said sounder comprising a direct current source of electricity, a rotary wheel of insulating material having a contact thereon, brushes adapted to engage said contact, connections between said brushes, said source of electricity and said sounder, an indicator, a commutator having a contact thereon, adjustable brushes adapted to engage said contact when said sounder is silent, and connections between said adjustable brushes, said receiving transmitter and said indicator whereby upon the proper adjustment of said adjustable brushes with relation to said contact said receiving trans nutter may operate said indicator.

15. In a device of the kind described, a sounder and a receiving transmitter, means for energizing said sounder comprising a source of electricity, a rotary wheel of insulating material having acontact thereon, brushes adapted to engage said contact, connections between said brushes, said source of electricity and said sounder, a telephone receiver, a commutator having. a. contact thereon, adjustable brushes adapted to engage said contact when said sounder is silent, and connections between said adjustable brushes, said receiving transmitter and 'said telephone receiver whereby upon the proper adjustment of said adjustable brushes with relation to said contact said receiving transmitter may operate said telephone receiver, and means for measuring the position of said brushes.

16. In a device of the kind described, a

10 with the breaking of. the sounder circuit sounder, and means for energizing it com-- prising a source of electricity, means for rendering said sounder silent, a receiving transmitter and means operable. when said sounder is silent to receive vibrations from said receiving transmitter.

17. A device for measuring prising an electrically energized sounder having a diaphragm and means forbringing the diaphragm to rest coincidentally consisting of a resistance connecting the termmals'of the'sounder. v '18. As a means for measur ngdistance,

a receiving transmitter, and an electrically energized. sounder having a diaphragm,- and means for damping the diaphragmcoincidentally with. the denergiz ing. of said sounder whereby the receiving transmitter will be energized by the echo only, said means consisting of a resistance connecting the terminals of said sounder.

19. The method of measuring ,distance which consists in, first, rendering irrespon'I- sivethe sound receiving mechanism, second,

varying the current in an electric circuit simultaneously with theproduction of the sound to be infiected,.thirdly, stopping the distance comtheir reception.

variation of the current flow, fourthly, damping 'the sending mechanism, and fifthly, rendering the receiving mechanism responsive.

20. The method of measuring distance which consists in causing the production of sound by varying the current in an electric circuit, then ceasing the current flow andsimultaneously damping the sound producer and rendering a receiving mechanism responsive..

21.'Th-at method of measuring distance .wh-ich consists in varying the current in vibrations," receiving said inflected vibra tions and measuring the elapsed time between the setting up of the vibrat'ons and REGINALD- A. FESSENDEN.

Witnesses:

GEORGE O. G. Com, M. E. FLAHZERTY. 

